St. Pauli in MünchenI noticed that the fish market is building up at Sendlingertor this year. Having only been to the real thing once, I'm not really sure if this would be like Oktoberfest in Hamburg, but I know people who make a point to go every year (ok, two of them are from Hamburg originally).
They have Fish-Semmel, with crawfishy things or "Bismarckhering" or you can get fish and chips thrown down the lighthouse chute. Apparently the Fishmarket mascot "BUTTJE" will be running around adding to the atmosphere of the market people flogging their wares at passers by.
The fishmarket in Hamburg is over 300 years old but is still a "thing to see" and is worth a look in Munich as well.